Ring Flash. The MADRF14C, N, S Marumi Ring Flash consists of a main control unit & a separate ring light which connects to the lens filter thread. This unit is ideal for Macro, Close-up photography due to the flash light being positioned directly between the camera lens & subject allowing for even, shadowless illumination. The flash has a guide number of 14 (metres) at 100 ISO with auto TTL metering. The lens mount is 52 mm, step-up rings are supplied for 55mm, 58mm, 62mm & 67mm. Powered by 4x AA batteries (not included). Available Models: Marumi DRF14C Ring Flashgun Canon MADRF14C. Marumi DRF14N Ring Flashgun Nikon MADRF14N. Marumi DRF14S Ring Flash Sony (MADRF14S).